Hardware – Sensors

The majority of measurements in the production version of the home hub utilised the DHT22/AM2302 temperature and humidity sensor.

DHT22/AM2302

The DHT22, AM2302 or equivalent has a number of benefits:

low cost

single-wire bus connection

interface software readily availableThe only drawback I have come across is the limitation of cable distance. In practice, even with corrective measures, the maximum distance from Pi to sensor is about 4m.

BME280

For this reason I have deployed the BME280 in situations where greater distances are involved. Fortunately the production version was installed in a bungalow, which permitted the majority of rooms to be reached using short cable runs from the centrally loft-mounted pi.

Unfortunately, the BME280 sensor requires additional circuitry to connect the Pi to its I2C or SPI interface. I will cover this in a later post.